The present invention relates to integrated circuit (IC) packaging, and more particularly to a lead frame for an integrated circuit device having both J-leads and Gull Wing leads.
FIG. 1 is a side view of a portion of a semiconductor device 10 comprising a plastic body 12 that houses one or more integrated circuits, and a plurality of leads projecting from a side thereof, where two such leads 14 and 16 are shown. The plastic body 12 protects the integrated circuitry, while the leads allow for external electrical connection to the integrated circuitry. In order to allow adjacent leads to be located close together (i.e., to reduce lead pitch), and therefore have more leads spaced around the body 12, some of the leads, like the lead 14, are bent outward, and other ones of the leads are bent inward, like lead 16. The outward bending leads are known as Gull Wing leads and the inward bending leads are known as J-leads.
FIG. 2 is a top plan view of a lead frame 20 used to assemble the integrated circuit device 10 of FIG. 1. The lead frame 20 comprises a generally rectangular die pad 22 surrounded by a plurality of leads 24. As noted above, the leads 24 are very close to one another. To prevent the leads from bending or contacting with adjacent leads, tape 26 is placed over the leads to hold them in place. Referring again to FIG. 1, it can be seen that the Gull Wing leads 14 extend from the side of the package body 12 at a different plane than the J-leads 16. Referring now to FIG. 3, during a molding process in which the plastic body 12 is formed, a portion 30 of the mold tooling 30 presses on an outer lead portion close to an inner lead portion of the leads 24 that will be formed into J-leads 16 so that the Gull Wing leads 14 and the J-leads 16 will be vertically spaced from each other, while an outer area of the outer lead portion of the leads 24 is clamped with another portion 32 of the mold tooling. Unfortunately, this pressing and lead deformation can cause the tape 26 to separate from the leads 24, as shown in the lower half of FIG. 3. Accordingly, a minimum lead pitch requirement may be violated or worse yet, one of the J-leads 16 may contact an adjacent Gull Wing lead 14, causing an electrical short circuit. Accordingly, it would be advantageous to have a lead frame and/or a method of preventing such a rule violation or short circuit condition.